''' This file provides a wrapper class for AWP (https://github.com/csdongxian/AWP) model for CIFAR-10 dataset. '''

import sys
import os

import torch
import torch.nn as nn
import torch.nn.functional as F
import tensorflow as tf

from ares.model.pytorch_wrapper import pytorch_classifier_with_logits
from ares.utils import get_res_path

MODEL_PATH = get_res_path('./cifar10/RST-AWP_cifar10_linf_wrn28-10.pt')


def load(_):
    model = AWP()
    model.load()
    return model


def filter_state_dict(state_dict):
    from collections import OrderedDict

    if 'state_dict' in state_dict.keys():
        state_dict = state_dict['state_dict']
    new_state_dict = OrderedDict()
    for k, v in state_dict.items():
        if 'sub_block' in k:
            continue
        if 'module' in k:
            new_state_dict[k[7:]] = v
        else:
            new_state_dict[k] = v
    return new_state_dict


@pytorch_classifier_with_logits(n_class=10, x_min=0.0, x_max=1.0,
                                x_shape=(32, 32, 3), x_dtype=tf.float32, y_dtype=tf.int32)
class AWP(torch.nn.Module):
    def __init__(self):
        torch.nn.Module.__init__(self)
        self.model = WideResNet(depth=28,
                                num_classes=10,
                                widen_factor=10).cuda()

    def forward(self, x):
        x = x.transpose(1, 2).transpose(1, 3).contiguous()
        labels = self.model(x.cuda())
        return labels.cpu()

    def load(self):
        checkpoint = filter_state_dict(torch.load(MODEL_PATH))
        self.model.load_state_dict(checkpoint)
        self.model.eval()


class BasicBlock(nn.Module):
    def __init__(self, in_planes, out_planes, stride, dropRate=0.0):
        super(BasicBlock, self).__init__()
        self.bn1 = nn.BatchNorm2d(in_planes)
        self.relu1 = nn.ReLU(inplace=True)
        self.conv1 = nn.Conv2d(in_planes, out_planes, kernel_size=3, stride=stride,
                               padding=1, bias=False)
        self.bn2 = nn.BatchNorm2d(out_planes)
        self.relu2 = nn.ReLU(inplace=True)
        self.conv2 = nn.Conv2d(out_planes, out_planes, kernel_size=3, stride=1,
                               padding=1, bias=False)
        self.droprate = dropRate
        self.equalInOut = (in_planes == out_planes)
        self.convShortcut = (not self.equalInOut) and nn.Conv2d(in_planes, out_planes, kernel_size=1, stride=stride,
                               padding=0, bias=False) or None
    def forward(self, x):
        if not self.equalInOut:
            x = self.relu1(self.bn1(x))
        else:
            out = self.relu1(self.bn1(x))
        out = self.relu2(self.bn2(self.conv1(out if self.equalInOut else x)))
        if self.droprate > 0:
            out = F.dropout(out, p=self.droprate, training=self.training)
        out = self.conv2(out)
        return torch.add(x if self.equalInOut else self.convShortcut(x), out)


class NetworkBlock(nn.Module):
    def __init__(self, nb_layers, in_planes, out_planes, block, stride, dropRate=0.0):
        super(NetworkBlock, self).__init__()
        self.layer = self._make_layer(block, in_planes, out_planes, nb_layers, stride, dropRate)
    def _make_layer(self, block, in_planes, out_planes, nb_layers, stride, dropRate):
        layers = []
        for i in range(int(nb_layers)):
            layers.append(block(i == 0 and in_planes or out_planes, out_planes, i == 0 and stride or 1, dropRate))
        return nn.Sequential(*layers)
    def forward(self, x):
        return self.layer(x)


class WideResNet(nn.Module):
    def __init__(self, depth, num_classes, widen_factor=1, dropRate=0.0):
        super(WideResNet, self).__init__()
        nChannels = [16, 16*widen_factor, 32*widen_factor, 64*widen_factor]
        assert((depth - 4) % 6 == 0)
        n = (depth - 4) / 6
        block = BasicBlock
        # 1st conv before any network block
        self.conv1 = nn.Conv2d(3, nChannels[0], kernel_size=3, stride=1,
                               padding=1, bias=False)
        # 1st block
        self.block1 = NetworkBlock(n, nChannels[0], nChannels[1], block, 1, dropRate)
        # 2nd block
        self.block2 = NetworkBlock(n, nChannels[1], nChannels[2], block, 2, dropRate)
        # 3rd block
        self.block3 = NetworkBlock(n, nChannels[2], nChannels[3], block, 2, dropRate)
        # global average pooling and classifier
        self.bn1 = nn.BatchNorm2d(nChannels[3])
        self.relu = nn.ReLU(inplace=True)
        self.fc = nn.Linear(nChannels[3], num_classes)
        self.nChannels = nChannels[3]

        for m in self.modules():
            if isinstance(m, nn.Conv2d):
                nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu')
            elif isinstance(m, nn.BatchNorm2d):
                m.weight.data.fill_(1)
                m.bias.data.zero_()
            elif isinstance(m, nn.Linear):
                m.bias.data.zero_()
    def forward(self, x):
        out = self.conv1(x)
        out = self.block1(out)
        out = self.block2(out)
        out = self.block3(out)
        out = self.relu(self.bn1(out))
        out = F.avg_pool2d(out, 8)
        out = out.view(-1, self.nChannels)
        return self.fc(out)


if __name__ == '__main__':
    if not os.path.exists(MODEL_PATH):
        if not os.path.exists(os.path.dirname(MODEL_PATH)):
            os.makedirs(os.path.dirname(MODEL_PATH), exist_ok=True)
        url = 'https://drive.google.com/file/d/1sSjh4i2imdoprw_JcPj2cZzrJm0RIRI6/view'
        print('Please download "{}" to "{}".'.format(url, MODEL_PATH))
